DNA extracted from museum specimens of the 19^th century provides a taxonomic resolution on the identity of the characid fish Psalidodon jequitinhonhae (Ostariophysi: Characiformes)

Psalidodon jequitinhonhae was originally proposed as a variety of Tetragonopterus rutilus, based on the analysis of 14 specimens from the Jequitinhonha River, Brazil. In 1910 it was relocated in Astyanax, as A. fasciatus jequitinhonhae in Tetragonopterinae and in 2020 in Psalidodon, as Stethaprioninae member. However, in none of these revisions, P. jequitinhonhae was morphologically redescribed. A short sequence of the Cytochrome c oxidase subunit I (COI) gene obtained from one of the syntypes is compared to sequences obtained from new samples, allowing the recognition of the species and its morphological redescription based on new specimens. Both morphological and molecular data converged and corroborated P. jequitinhonhae as a valid species, occurring in the Jequitinhonha and Pardo river basins in Brazil. The syntype that provided the analyzed COI sequence is referred to as the lectotype by present designation.